DESCRIPTION (Investigator's) Abstract): Despite intensive investigative efforts over the past several decades, causative factors can be identified for only a relatively small percent of the developmental defects reported in humans. During the last decade there has been increasing interest in the idea that maternal nutritional status may be a critical factor for normal human embryonic and fetal development. For example, during the last few years there has been considerable controversy about the hypothesis that the use of multivitamin/multimineral supplements during pregnancy is associated with a reduced risk of birth defects and other aspects of abnormal development; this controversy is due in part to a lack of consensus on the extent to which modest to severe changes in the nutritional environment of the embryo and fetus influence development. This lack of consensus can also be attributed to the fact that until recently, there was little information on how, mechanistically, specific nutrients affect development. However, due to the development of novel in vitro methodologies, and the application of advanced molecular biology techniques, there has been a recent upsurge in the investigators' understanding of the role of specific nutrients in embryonic and fetal development. One problem in dissemination of the advances made in this area is that investigators with different backgrounds and expertise lack a common forum to share and discuss their results. To better integrate the results obtained from human pregnancy studies, and from experimental animal work, basic scientists in biochemistry, cell and molecular biology, embryology and nutrition need to meet with clinicians with expertise in obstetrics, physiology and epidemiology. The investigators are proposing an international conference which will be concerned with: (1) the investigation of mechanisms underlying the role of specific nutrients in prenatal development, 2) the influence of specific nutrient deficiencies on prenatal development in experimental models, and 3) the critical examination of current information on the influence of maternal nutritional status on pregnancy outcome in human populations.